Polycarbonates obtained from diphenols are known and, because of their good mechanical, thermal and electrical properties, have gained acceptance in many fields of industrial use.
A certain disadvantage of the polycarbonates obtained from diphenols is that their resilience properties such as, for example, their notched impact strength and their splintering properties, are inadequate for special applications at low temperatures. A further disadvantage is that the toughness in the case of high wall thicknesses is sometimes inadequate. The tough fracture occurring at low wall thicknesses turns into a brittle fracture at higher wall thicknesses. The transition region is called the "critical thickness" (4 to 6 mm).
It is known to improve the resilience properties of polycarbonates obtained from diphenols by, for example, admixing ABS graft copolymers: compare, for example, German Pat. No. 1,170,141 and German Published Patent Specification No. 1,900,756 which corresponds to U.S. Pat. No. 3,663,471. However, disadvantages are the loss in transparency and the deterioration of some thermal properties, such as, for example, the heat distortion point according to DIN 53,460.
It has now surprisingly been found that by admixing polyether-carbonates and/or polyester-carbonates, products are obtained which are distinguished by improved resilience properties compared with known polycarbonates, especially at low temperatures and at increased critical thickness, while retaining other typical polycarbonate properties such as transparency and heat distortion point.